System, method and computer-accessible medium for tracking vessel motion during three-dimensional coronary artery microscopy

ABSTRACT

Exemplary embodiments of apparatus, method and computer accessible medium can be provided which can facilitate a determination of at least one characteristic of a structure. For example, it is possible to use at least one first arrangement which can be structured to provide at least one first transmitted radiation along a first axis and at least one second transmitted radiation along a second axis. The first and second transmitted radiations can impact the structure and generate respective first and second returned radiation. The first and second axis can be provided at a predetermined angle with respect with one another which is greater than 0. Further, at least one second arrangement can be provided which can be configured to receive data associated with the first and second returned radiations, and determine at least one relative velocity between the structure and the first arrangement along the first and second axes.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority fromU.S. Patent Application Ser. No. 61/051,231, filed on May 7, 2008, theentire disclosure of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to exemplary embodiments of systems,methods and computer-accessible medium for monitoring of relativespatial locations or motions between an instrument and a sample, andmore particularly to exemplary embodiments of systems, methods andcomputer-accessible medium for tracking vessel motion during, e.g., athree-dimensional coronary artery microscopy procedure.

BACKGROUND INFORMATION

In certain applications, it can be desirable to monitor the relativelocation or motion between two objects. For example, in certainapplications, it can be beneficial to precisely direct a well-definedbeam or sensing vector along particular directions or at specificlocations with respect to a sample. It can therefore be important toprovide knowledge about the relative location or motion between the beamor sensing vector and the sample. In several laser procedures, forexample, it can be desirable to scan a laser beam across a sampleaccording to a predetermined scan pattern or at specific locations. Incases where the sample may undergo uncontrolled motion, the precisionwith which the predetermined scan pattern or specific location can beachieved can be compromised. In certain sensing or imaging applications,it can be important to control the sensing point or axis with respect toa sample. In order to generate two- or three-dimensional images, thesensing point or axis can be scanned with respect to the sampleaccording to a predetermined pattern. For accurate imaging reproductionof the structure of the sample, it can be important that thepredetermined scan pattern is precisely followed. In the presence ofuncontrolled sample motion, the actual scan pattern on or within thesample can differ from the predetermined scan pattern and image fidelitycan be compromised.

One general category of strategies that can be commonly followed formonitoring the spatial location or motion between two objects is tomonitor the location or motion of each objects with respect to a knownor controlled reference point. This type of strategy can be relevant incases where one object and the reference point are persistently locatedwith respect to one another. In medical catheter-based imagingapplications, for example, the signal transducer can be placed at thedistal end of a catheter, which can be inserted within an animal orhuman body. The transducer can be connected to an actuator at a proximalend of the catheter using an axially non-extensible, torque-conveyingelement such that as the actuator rotates or pushes or pulls theelement, the actuator's motion is replicated accurately at thetransducer. When the tissue or organ that is being imaged is not moving,and further, when the imaging system is not moving, then the constraintthat one object and the reference point can be fixed with respect to oneanother is met. Therefore, the relative location and/or motion of thetransducer with respect to the organ or tissue can be monitored andcontrolled. In some cases, however, the organ or tissue may undergomotion, e.g., due to respiration, cardiac function, peristalsis orpatient motion, and this general category of strategy may not beapplicable. Further, motion within the body, along the length of thecatheter, can result in an uncontrolled motion of a distal end and ofthe transducer of the catheter with respect to the tissue of interest.

In certain medical procedures, it can be preferable to monitor thelocation and/or motion of an instrument with respect to a specificanatomical location or organ. An exemplary strategy to accomplish thisobjective can be to prepare the instrument so that it can be detected byan imaging modality that also facilitates a detection of the specificanatomical location or organ. In certain cases, however, the anatomicallocation or organ may not exhibit sufficient contrast for detection. Forexample, by fluoroscopy or X-ray computed tomography, the soft-tissuesof the body can exhibit low relative contrast. For example, coronaryarteries may not, therefore, be located with these techniques withoutthe use of exogenous contrast agents. Furthermore, certain conventionalimaging technologies may not have a sufficient resolution to preciselydetermine the relative location or motion of an instrument with respectto a specific anatomical location or organ.

The above-described issues and deficiencies are merely representative ofa need for more precisely monitoring the relative location or motionbetween two objects. Indeed, it may be beneficial to address and/orovercome at least some of the deficiencies described herein above.

SUMMARY OF THE INVENTION

In order to overcome at least some of the deficiencies described above,exemplary embodiments according to the present disclosure can beprovided for accurately monitoring the relative location and/or motionbetween two objects. In one exemplary embodiment, one object can beconfigured to emit an acoustic or electromagnetic radiation, which maybe scattered by the second object. The first object can be furtherconfigured to collect at least a portion of the scattered acoustic orelectromagnetic radiation and process this signal to determine therelative distance and/or relative velocity between the two objects. Inanother exemplary embodiment of the present disclosure, the first objectcan be facilitated to provide two or more distinct acoustic orelectromagnetic radiations, which can be directed along distinctpropagation axes having predetermined angles with respect to oneanother, and which can further scatter from the second object. In thisembodiment, the first object may be further configured to collect two ormore of the scattered acoustic or electromagnetic radiations and toprocess the corresponding signals in order to determine the relativemotion of the two objects in two or more spatial dimensions.

According to still another exemplary embodiment of the presentdisclosure, a medical catheter can be provided which is configured todeliver at least one beam of light that may be reflected by a specificanatomical location or biological organ. The exemplary catheter can befurther configured to detect the reflected light and to process thissignal to determine the relative distance and/or relative velocitybetween the catheter and the biological site. Exemplary embodiments ofmethods for processing the signal can be based on the Doppler frequencyshift imparted on the reflected light by the motion of the secondobject. By tracking the relative velocity over time, the distancebetween the two objects may be monitored. The medical catheter can befurther configured to deliver multiple light beams, having distinctwavelength components and directed through distinct spatial angles withrespect to one another so that the relative velocity vector between thecatheter and the specific anatomical site or biological organ can bedetermined.

Thus, according to certain exemplary embodiments of the presentdisclosure, apparatus, method and computer accessible medium can beprovided which can facilitate a determination of at least onecharacteristic of a structure. For example, it is possible to use atleast one first arrangement which can be structured to provide at leastone first transmitted radiation along a first axis and at least onesecond transmitted radiation along a second axis. The first and secondtransmitted radiations can impact the structure and generate respectivefirst and second returned radiation. The first and second axis can beprovided at a predetermined angle with respect with one another which isgreater than 0. Further, at least one second arrangement can be providedwhich can be configured to receive data associated with the first andsecond returned radiations, and determine at least one relative velocitybetween the structure and the first arrangement along the first andsecond axes.

In another exemplary embodiment of the present disclosure, the first andsecond transmitted radiations can be electro-magnetic radiations and/orultrasound radiations. Further, the first and second transmittedradiations can have different wavelengths. In addition, the data cancorrespond to a Doppler shift between the first and second transmittedradiations and the first and second returned radiations. The data canalso correspond to, e.g., a time rate of change of a distance betweenthe apparatus and the structure along the first and second axes.

According to still another exemplary embodiment of the presentdisclosure, the first arrangement can extend along a longitudinal axis,and a first velocity along the first axis and a second velocity alongthe second axis can be used to determine a further relative velocitybetween the apparatus and the structure at least approximately along thelongitudinal axis. In addition, a position and/or a rotation of theapparatus can be determined based on the further relative velocity.Further, at least one third arrangement which can be configured togenerate at least one image of at least one portion of the structure asa function of the relative velocity. For example, the third arrangementcan generate the image using an optical frequency domain interferometricprocedure, an optical coherence interferometric procedure and/or anultrasound procedure. At least a portion of the third arrangement isprovided in a catheter.

In yet another exemplary embodiment of the present disclosure, the firstarrangement can include a portion having a section which is structuredto reflect at least one of the first and/or second transmittedradiations and at least partially to allow to pass therethrough theother one of the first and/or second transmitted radiations based onrespective wavelengths of the first and second transmitted radiations.For example, the reflected radiation and the pass through radiation canbe provided at the predetermined angle. Further, the first arrangementcan be structured to collimate and/or focus the first transmittedradiation and/or the second transmitted radiation. In addition, thefirst and second axes can impact the structure at positive and negativeangles, respectively, with respect to an axis perpendicular to a surfaceof the structure. The second arrangement can be further configured todistinguish between a relative motion between the structure and thefirst arrangement in two dimensions based on the first and secondreturned radiations.

These and other objects, features and advantages of the exemplaryembodiment of the present disclosure will become apparent upon readingthe following detailed description of the exemplary embodiments of thepresent disclosure, when taken in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE DRAWING(S)

Further objects, features and advantages of the present invention willbecome apparent from the following detailed description taken inconjunction with the accompanying figures showing illustrativeembodiments of the present invention, in which:

FIG. 1 is a side cross-sectional view of a catheter which utilizes aconventional scanning technique for a three-dimensional imaging;

FIG. 2 is a side cross-sectional view of a catheter according to anexemplary embodiment of the present invention for tracking relativedistance and/or motion between a conduit within the catheter and alumen;

FIG. 3 is a diagram of an exemplary embodiment of a system/apparatusaccording to the present disclosure for processing signals returned fromthe exemplary catheter shown in FIG. 2;

FIG. 4 is a pair of graphs illustrating plots of data acquired by theexemplary system/apparatus shown in FIG. 3 for tracking the relativemotion between a catheter conduit and a target (e.g., a lumen);

FIG. 5 is a side cross-sectional view of an exemplary embodiment ofcertain components of the exemplary catheter shown in FIG. 2, which canbe used for monitoring the relative motion and/or velocity between thecatheter conduit and the target; and

FIG. 6 is a flow diagram of an exemplary embodiment of a methodaccording to the present disclosure for determining at least onecharacteristic of a structure.

Throughout the figures, the same reference numerals and characters,unless otherwise stated, are used to denote like features, elements,components or portions of the illustrated embodiments. Moreover, whilethe subject disclosure will now be described in detail with reference tothe figures, it is done so in connection with the illustrativeembodiments. It is intended that changes and modifications can be madeto the described exemplary embodiments without departing from the truescope and spirit of the subject disclosure as defined by the appendedclaims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a side cross-sectional view of an example of a conventionalcatheter using which monitoring of relative spatial locations or motionsbetween two objects would likely be beneficial. Turning to FIG. 1, whendelivering light, e.g. for imaging or therapy, through such catheter oran endoscope to the lumen 100 of an internal organ 100, it is possibleto utilize a catheter comprising an external sheath 110 and an internalconduit 120 that can be rotated and/or translated within the sheath.When the conduit 120 is configured to deliver light along a particularaxis 130, the exposure of light to a predetermined portion of the lumen100 can be achieved by rotating and longitudinally scanning the conduitwhile also controlling the irradiance delivered by the conduit. Forexample, this strategy can be utilized for imaging the lumen 100. Insuch cases, it can be important that the resulting helical scan pattern140 exposes the entire surface area of the lumen 100.

Typically, the sheath may be held fixed with respect to the lumen 100,and the location and orientation of the conduit can be remotelymonitored with respect to the sheath. In this manner, the scan patternof the light on the lumen 100 can be controlled. However, in instanceswhen the relative location or motion of the sheath with respect to thelumen may not be controlled, the accuracy of the scan pattern can nolonger be assured. This can be due to, for example, from respiration,peristalsis, cardiac function, or other sources of motion. Although suchrepresentative example of delivering light to the lumen of an internalbiological organ can instructive for understanding a context of theexemplary embodiments of the present disclosure, it by no meansrepresents the only application for which monitoring of the relativespatial location or motion between two objects would be beneficial.

FIG. 2 shows a side cross-sectional view of a catheter according to anexemplary embodiment of the present invention for tracking relativedistance and/or motion between a conduit within the catheter and alumen. According to such exemplary embodiment as illustrated in FIG. 2,the exemplary catheter 250 can be provided which can be suitable forimaging internal biological organs. Such exemplary catheter 250 can bestructured or configured to include an internal conduit 210, which canbe provided within an external and at least partially transparent sheath211. The conduit can be configured or designed to emit electromagneticradiation (e.g., light) or ultrasound radiation along two distinct axes220 and 230 in such a way that a relative orientation between the twoaxes 220, 230 can be quantified by a relative angle 240.

When reflected or scattered radiation is returned along each of the axes220, 230, such returned radiation can be collected by the conduit 210,and conveyed proximally within the catheter to an attached or coupledreceiver and/or a processing arrangement (e.g., which can include aprocessor). Through the measurement of the reflected and/or scatteredradiation, the magnitude of the relative velocity and/or the relativedistance between the conduit 210 and the lumen along the respective axis220, 230 can be determined. Further, since the relative angle betweenthe two axes 220, 230 can be known and/or determined, comparing thevelocity magnitude measurements along each axis can further provide thedirection of the relative velocity.

In certain exemplary embodiments of the present disclosure, measurementsof the relative distance and or velocity along certain specified axes220, 230 between the conduit 210 and the lumen may be used to correctfor motion arising from, for example, peristalsis, cardiac function,respiration, or other sources of motion. Such exemplary measurements canbe used, for example, to alter a scan pattern of the conduit 210 withrespect to the sheath 211 so that a uniform, pre-determined scan patterncan result between the conduit and the lumen 100. Certain exemplarymethods and/or techniques known in the field of medical imaging can beused for controlling the scan patterns of conduits within catheters,including, e.g., external motors, located at the proximal catheter endand attached to the conduit and sheath, internal motors located withinthe sheath for rotating and or translating the conduit with respect tothe sheath, and miniature electromechanical, galvanometric, and/ormagneto-mechanical actuators for rotating and or translating the conduitwith respect to the sheath. Alternatively or in addition, such exemplaryactuators can be used to control the orientation of the optical axesdirectly.

According to certain exemplary embodiments of the present disclosure, itis possible to apply methods of low-coherence interferometry todetermine the distance between the conduit 210 and the lumen. Suchexemplary measurements can include coherence-domain ranging,frequency-domain ranging, and time-domain ranging. In such exemplaryembodiments of the present disclosure, further processing of distancemeasurements can be applied to determine a relative velocity between theconduit 210 and the lumen. For example, the distance measurements can bemonitored over time to provide a derivative which can be proportional tothe relative velocity.

According to further exemplary embodiments of the present disclosure, itis possible to utilize measurements that can provide a magnitude of therelative velocity along the specified axes 220, 230. Such exemplarymeasurements can be integrated to provide the relative distances and caninclude, but are certainly not limited to, exemplary measurements suchas the rate of temporal decorrelation of a speckle pattern or theDoppler frequency shift imparted on the reflected or scattered light,etc. In the presence of relative motion between a conduit and a lumen,the radiation (e.g., light) reflected, for example, along the axes 220,230 can be frequency shifted and/or Doppler shifted by an amount thatcan depend on the relative velocity, the incidence angle θ, and/or thetracking wavelength λ:

$\begin{matrix}{{f_{D} = {\frac{2}{\lambda}\left( {{v_{r}\cos \; \theta} + {v_{z}\sin \; \theta}} \right)}},} & (1)\end{matrix}$

where ν_(r) and ν_(z) are, respectively, the relative radial andlongitudinal velocities of the lumen with respect to the conduit.Because the exemplary radiation provided via the axes 220, 230 impactand/or illuminate the lumen at different angles, such exemplary beamsand/or radiations can experience different Doppler shifts for the samevelocities:

$\begin{matrix}{\begin{pmatrix}f_{1} \\f_{2}\end{pmatrix} = {\frac{2}{\lambda}\begin{pmatrix}{\cos \; \theta_{1}} & {\sin \; \theta_{1}} \\{\cos \; \theta_{2}} & {\sin \; \theta_{2}}\end{pmatrix}{\begin{pmatrix}v_{r} \\v_{z}\end{pmatrix}.}}} & (2)\end{matrix}$

For example, if the first and second exemplary beams and/or radiationsimpact and/or illuminate the surface of the lumen at positive andnegative angles, respectively, with respect to an axis perpendicular tothe surface of the lumen, then the first and second exemplary beamsand/or radiations can be used to distinguish relative motion between thelumen and the catheter in the longitudinal and radial directions. Incertain exemplary embodiments employing such exemplary geometry, motionof the lumen in the +z direction (e., along the axis of the lumen)relative to the conduit 210 can cause the first exemplary beam and/orradiation to shift up in frequency, while simultaneously causing thesecond exemplary beam and/or radiation to shift down in frequency. Forexample, motion of the lumen in the −z direction can cause the firstexemplary beam and/or radiation to shift down in frequency, whilesimultaneously causing the second exemplary beam and/or radiation toshift up in frequency.

At the same time, e.g., motion of the lumen in the +r direction (e.g.,of the lumen towards the catheter) can cause both beams and/orradiations to shift up in frequency; whereas, motion in the −r directioncan cause both beams and/or radiations to shift down in frequency. Thus,relative motion in the two dimensions can be resolved because the beamsand/or radiations experience oppositely directed Doppler shifts formotion along a first dimension and Doppler shifts in the same directionfor motion along the second dimension. Those having ordinary skill inthe art will certainly understand that adding a third beam and/orradiation at an appropriate angle can facilitate a resolve relativemotion in a third dimension (and/or improve the accuracy of measurementsin the first and second dimensions).

Those having ordinary skill in the art will further certainly understandthat a beam transmitted along an axis normal to the surface of the lumenwould likely not experience a Doppler shift for relative longitudinalmotion. Motion in the two directions can still be resolved according tocertain exemplary embodiments employing such a geometry. This isbecause, for example, the other beam and/or radiation can stillexperience a Doppler shift for longitudinal motion. Thus, the radialmotion can cause both beams and/or radiations to experience a Dopplershift; whereas, longitudinal motion can cause only one beam and/orradiation to experience a Doppler shift. This difference can facilitatethe ability to distinguish the two directions of motion.

Equation (2) illustrates that the exemplary frequency shift measurementsalong the two axes 220, 230 can form a basis set (e.g., not anorthonormal set) for resolving the two relative velocity components ofthe lumen with respect to the conduit. Inverting the matrix in Eq. (2)can provide the relative velocities in terms of the incidence angles andthe measured Doppler shifts:

$\begin{matrix}{\begin{pmatrix}v_{r} \\v_{z}\end{pmatrix} = {\frac{\lambda}{2\; {\sin \left( {\theta_{2} - \theta_{1}} \right)}}\begin{pmatrix}{\sin \; \theta_{2}} & {{- \sin}\; \theta_{1}} \\{\cos \; \theta_{2}} & {\cos \; \theta_{1}}\end{pmatrix}{\begin{pmatrix}f_{1} \\f_{2}\end{pmatrix}.}}} & (3)\end{matrix}$

In certain exemplary applications, it is possible to configure orprovide the optical axes 220, 230 such that one of the axes 220, 230 canbe approximately normal to the lumen, so that relative velocity ordistance measurements along this axis represent radial relative motion.Further, it is possible to configure or provide the optical axes 220,230 such that the relative angle 240 between them is greater than, e.g.,approximately 45 degrees but less than, e.g., approximately 90 degrees.Exemplary measurements of Doppler frequency shifts can be facilitated bymixing light returning along the optical axes with light from a localoscillator, or heterodyne reference, which can be coherent with theradiation (e.g., the light) emitted from the conduit, along the axes220, 230.

FIG. 3 illustrates an exemplary embodiment of a system/apparatusaccording to the present disclosure for processing signals returned fromthe exemplary catheter shown in FIG. 2. For example, a beam director340, for example, a wavelength division multiplexer, can be provided ata proximal end of a conduit 320 that can transmit a returned radiation(e.g., light) so that it can be combined with the radiation (e.g.,light) from a local oscillator using a coupler 380. Radiation (e.g.,light) returned along each axis can be further separated and/or detectedby separate receivers 390. The detected signal associated with radiation(e.g., light) returning along one of the first and second axes 220 canbe subject to the following exemplary approximation,

I(t)≈I _(LO)+√{square root over (I_(LO) I ₁)} cos [2π(f _(LO) −f₁)t],  (4)

where I_(LO) is the local oscillator intensity, f_(LO) is the localoscillator frequency, and I₁ is the intensity of the returned lightcorresponding to axis 1. An exemplary knowledge and/or determination ofthe frequency of the local oscillator can therefore be utilized todetermine the frequency of the returned light, and using Equation 3, todetermine the corresponding relative velocity.

For example, a heterodyne reference beam can serve, e.g., two purposes:i) amplifying the signal, and/or ii) making it possible to distinguishthe direction of motion. For example, if f_(LO)=0, approximately equalbut oppositely directed velocities may produce signals that oscillate atthe same frequency. When f_(LO)>f₁f₂, approximately equal but oppositelydirected velocities may cause the detected signal to shift away from thelocal oscillator frequency in opposite directions, removing thisambiguity.

The signal-to-noise ratio (SNR) of the detected signal can limit theprecision of the frequency measurement, which, in turn, limits theprecision of the velocity estimate. In addition, any difference betweenthe actual angles of incidence from the assumed angles of incidence canresult in errors in the velocity estimate. Because the tracking beamand/or radiation can refract through the facet over a small range ofangles, however, the Doppler shift of the refracted beam and/orradiation can span a small range of frequencies centered at the nominalDoppler frequency, f₂. If the angle of incidence changes, the angularspread can change as well, likely causing, e.g., the peak at f₂ tobecome broader or narrower. Similarly, angular spread in the reflectedbeam and/or radiation can affect the shape of the peak at f₁.

Alternatively or in addition, according to a further exemplaryembodiment of the present disclosure, another optical elementcantilevered from the probe tip or suspended in the sheath can be usedto reflect and possibly collimate or focus the refracted beam and/orradiation towards the spot being imaged. Collimating the beam and/orradiation can sharpen the Doppler-shifted peak, as would likelyfocusing, provided that the angular spread of the focused beam and/orradiation is smaller the angular spread of the refracted beam and/orradiation alone.

In semi-rigid lumens, projecting both tracking beams and/or radiationsonto the same spot can also improve the accuracy of velocity estimationas long as the interbeam angle (e.g., θ₁-θ₂) can remain large. In asemi-rigid vessel, e.g., different parts of the vessel can move atdifferent velocities, e.g., likely degrading the velocity estimate madeby measuring the Doppler shifts of beams and/or radiations illuminatingdifferent spots. Bringing the tracking beam/radiation spots closetogether while maintaining a large interbeam angle can reduce oreliminate such problem, while possibly preserving tolerance to angularmisalignment.

In further exemplary embodiments of the present disclosure, additionaloptical axes (>2) can be utilized and reflected or scattered lightcorresponding to each axis may be processed to yield relative distanceand or velocity using the exemplary methods and procedures describedabove. This additional information can be useful for decreasingsensitivity of measurements to noise or to improve the accuracy withwhich the relative distance, velocity or direction of velocity can bedetermined.

Further exemplary embodiments according to the present disclosure can bedirected to techniques, apparatus and computer accessible medium thatfacilitate a unique identification of each optical axis. Such exemplarytechniques, apparatus and computer-accessible medium can include, e.g.,wavelength division multiplexing, time division multiplexing andfrequency division multiplexing. For example, turning back to FIG. 3,this figures illustrates a wavelength-division multiplexing instrument310 for determining the relative distance and or velocity of a catheterconduit 320 with respect to a lumen. For example, actuators 330 can belocated at the proximal end of the catheter to control the rotation andor longitudinal location of the distal conduit end.

A wavelength division multiplexer 340 can be used to deliver radiation(e.g., light) from the instrument 310 into an imaging system, which cancomprise a console 335, the actuators 330 and a catheter conduit 320.The exemplary instrument 310 can include multiple independent lightsources 350 and 360, which can be combined into a single optical pathusing a wavelength division multiplexer 370. The radiation (e.g., light)sources can be uniquely identified by their wavelength or by frequencyor amplitude modulation patterns incorporated into their emission. Thesingle optical path can be subsequently divided into two paths, one pathwhich can be in communication with the imaging system and another pathrepresenting a reference path.

The use of modulators 395, such as but not limited to acousto-optic,electro-optic or magneto-optic, can improve the sensitivity of detectionof the desired relative velocity and or relative distance parameters.For example, radiation (e.g., light) from each path, includingradiation/light returning from the lumen, can be recombined using thecoupler 380, and directed to the receiver 390. The receiver 90 can beconfigured to separate the optical signals into paths corresponding toeach independent light source and to measure, for example, the Dopplerfrequency shift or delay corresponding to the relative distance and ormotion of the catheter conduit with respect to the lumen. Theincorporation of the modulator or frequency shifter 395 into thereference path can be useful, e.g., for overcoming noise in the system.

FIG. 4 shows a pair of graphs illustrating plots of data acquired by theexemplary system/apparatus shown in FIG. 3 for tracking the relativemotion between a catheter conduit and a target (e.g., a lumen). Forexample, a trace 410 represents data acquired by the exemplaryembodiment of FIG. 3, and can display a time varying Doppler frequency,which can be proportional to the actual relative velocity between aconduit and a sample. A trace 420 depicts a theoretical Doppler shift,corresponding to the actual relative motion.

The combination of the exemplary embodiments of the present disclosurewith techniques, such as ultrasonic imaging or therapy and opticalimaging or therapy, be readily achieved as should be understood by thosehaving ordinary skill in the art after reviewing the present disclosure.For example, in the exemplary embodiments, the axes 220, 230 that can beutilized to determine relative distance and or velocity can be deliveredin a spatially co-registered orientation with respect to the imaging ortherapy axes. Further, one of the axes 220, 230 can be one of the axesused for imaging or therapy. In this example, the axis 220 can representboth an imaging or therapy axis and an axis for determining relativedistance and or velocity. For ultrasound and optical imaging techniques,this exemplary combination can be achieved.

Further exemplary embodiments of the present disclosure can be furtherconfigured to control the relative orientation of the axes 220, 230along which relative distances or velocities may be determined. Forexample, as shown in one exemplary embodiment configured for registeringthe relative distance and or motion in conjunction with optical imagingas illustrated in FIG. 5, an optical transducer 510 can be configured todirect two or more optical axes in predetermined directions. Anexemplary transducer 510 can include reflective, refractive and ordiffractive surfaces. For example, one such exemplary dichroicreflective surface 520 can be configured to reflect radiation (e.g.,light) of specific wavelengths and transmit radiation (e.g., light)having different wavelengths.

Dichroic filters can be constructed using dielectric coatings or facetsat discontinuities of refractive indices, as is well known in the art.One exemplary configuration can include another exemplary dichroicsurface 520 for which radiation (e.g., light) having wavelengths lowerthan a predetermined value may be reflected, and radiation (e.g., light)having a longer wavelength may be transmitted. This exemplaryconfiguration can be utilized to produce two distinct axes 530, 540.Further, the optical transducer 510 can be configured to include arefractive facet 550 which can be distal to the dichroic surface suchthat radiation (e.g., light) transmitted through a facet 550 follows anaxis 540 that is inclined in a forward direction.

Alternatively or in addition, the facet 550 can be followed by areflective surface, such as, e.g., a mirror, oriented to provide anydirectional orientation of axis 540. An optical transducer 510 canfurther be configured to focus light along one or more of the axes to apredetermined focal plane. In this exemplary embodiment, the axis 530can include more than one optical beam. For example, the axis 530 caninclude light used for determining relative distance and or velocityaccording to the exemplary embodiment of the present disclosure, as wellas light used for imaging or treating the biological lumen.

In further exemplary embodiments of the present disclosure, theexemplary techniques, apparatus and methods of the present disclosurecan be implemented using other forms of propagating energy rather thanlight. Such exemplary embodiments can utilize, e.g., ultrasonic energyto determine the relative distance or the relative velocity between atransducer and lumen. FIG. 6 shows flow diagram of an exemplaryembodiment of a method according to the present invention determining atleast one characteristic of a structure which can be executed by aprocessing arrangement, and memorialized, e.g., using software stored orprovided on a computer-accessible medium (e.g., hard drive, floppy disk,memory device such as a memory stick of other memory or storage device,or ac combination of one or more thereof).

In particular, as shown in FIG. 6, at least one first transmittedradiation can be provided along a first axis and at least one secondtransmitted radiation can be provided along a second axis using aparticular arrangement (procedure 510). For example, the first andsecond transmitted radiations can impact the structure and generate atrespective first and second returned radiation, and the first and secondaxis can be provided at a predetermined angle with respect with oneanother which is greater than 0. Further, as provided in procedure 520,data associated with the first and second returned radiations can bereceived. In addition, at least one relative velocity between thestructure and the particular arrangement along the first and second axescan be determined (procedure 530).

The foregoing merely illustrates the principles of the invention.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.Indeed, the arrangements, systems and methods according to the exemplaryembodiments of the present invention can be used with and/or implementany OCT system, OFDI system, SD-OCT system or other imaging systems, andfor example with those described in International Patent ApplicationPCT/US2004/029148, filed Sep. 8, 2004, U.S. patent application Ser. No.11/266,779, filed Nov. 2, 2005, and U.S. patent application Ser. No.10/501,276, filed Jul. 9, 2004, the disclosures of which areincorporated by reference herein in their entireties. It will thus beappreciated that those skilled in the art will be able to devisenumerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of theinvention and are thus within the spirit and scope of the presentinvention. In addition, to the extent that the prior art knowledge hasnot been explicitly incorporated by reference herein above, it isexplicitly being incorporated herein in its entirety. All publicationsreferenced herein above are incorporated herein by reference in theirentireties.

1-20. (canceled)
 21. An apparatus for determining at least onecharacteristic of a structure, comprising: at least one transceiverfirst arrangement which is structured to provide at least one firsttransmitted radiation along a first axis and at least one secondtransmitted radiation along a second axis, wherein the first and secondtransmitted radiations impact the structure and generate respectivefirst and second returned radiation, and wherein the first and secondaxes are provided at a predetermined angle with respect with one anotherwhich is, greater than 0; at least one computer second arrangement whichis configured to receive data associated with the first and secondreturned radiation, and determine at least one relative velocity betweenthe structure and the at least one first arrangement; and at least oneimaging third arrangement which is configured to generate at least oneimage of at least one portion of the structure as a function of the atleast one relative velocity.
 22. The apparatus according to claim 21,wherein the first and second transmitted radiations are electro-magneticradiations.
 23. The apparatus according to claim 21, wherein the firstand second transmitted radiations have different wavelengths.
 24. Theapparatus according to claim 21, wherein the data corresponds to aDoppler shift between the first and second transmitted radiations andthe first and second returned radiations.
 25. The apparatus according toclaim 21, wherein the data corresponds to a time rate of change of adistance between the apparatus and the structure along the first andsecond axes.
 26. The apparatus according to claim 21, wherein the atleast one first arrangement extends along a longitudinal axis, andwherein a first velocity along the first axis and a second velocityalong the second axis is used to determine a further relative velocitybetween the apparatus and the structure at least approximately along thelongitudinal axis.
 27. The apparatus according to claim 26, wherein atleast one of a position or a rotation of the apparatus is determinedbased on the further relative velocity.
 28. The apparatus according toclaim 21, wherein the at least one third arrangement generates the atleast one image using an optical frequency domain interferometryprocedure.
 29. The apparatus according to claim 21, wherein the at leastone third arrangement generates the at least one image using an opticalcoherence interferometry procedure.
 30. The apparatus according to claim21, wherein the at least one third arrangement generates the at leastone image using an ultrasound procedure.
 31. The apparatus according toclaim 21, wherein at least a portion of the at least one thirdarrangement is provided in a catheter.